Alkenyl succinic anhydrides ("ASA") are used as sizing agents, bleach activators and as corrosion inhibitors and detergents in petroleum products. They are also readily converted to derivatives such as esters, amides and imides useful in petroleum products.
The thermal process of making ASA requires heating of an olefin and maleic anhydride ("MA") to fairly high temperatures on the order of 175.degree.-275.degree. C. If desired the reaction can be promoted by addition of chlorine. Some degradation occurs in the reaction mixture caused by homopolymerization of MA and copolymerization of MA and olefin leading to discoloration and formation of tar and particulates. These decomposition products have an adverse effect on the color and performance of ASA in many of its leading markets such as paper size.
Attempts have been made to inhibit the formation of tar in the reaction of olefin with MA. Key et al., GB 1,337,724, describe the use of certain phosphorus-containing sequestrants, e.g. triphenylphosphite and hydroxy aromatics to inhibit tar formation in making ASA for use as a detergent builder.
Irwin et al., U.S. Pat. No. 3,412,111, describe the use of hydroxy aromatics, e.g. hydroquinone, and amino aromatics, e.g. phenothiazine, to inhibit polymer formation during preparation of ASA.
Puskas et al., U.S. Pat. No. 3,935,249, disclose the use of small amounts of inorganic halogen compound such as dry HCl or calcium bromide to prevent tar formation.
Zaweski et al., U.S. Pat. No. 3,476,774, report the use of hindered phenols, e.g. 4,4'-methylenebis(2,6-di-tert-butylphenol) and 1,3,5-trimethyl-2,4,6-tri(3,5-di-tert-butyl-4-hydroxybenzyl) benzene, to prevent decomposition of the reactants.
Kao Soap in Japan 56/12382 describe the use of certain phosphite esters, e.g. tributyl phosphite, in making ASA. Japan 60/78975 report the use of a combination of trialkyl phosphite, e.g. trioctyl phosphite, and dihydroxy aromatic, e.g. 2,5-di-tert-butylhydroquinone, in the preparation of ASA.